src/runtime/runtime-typedarray.cc - v8/v8.git - Git at Google

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include "src/runtime/runtime-utils.h"

 #include "src/arguments.h"
 #include "src/factory.h"
 #include "src/messages.h"
 #include "src/objects-inl.h"
 #include "src/runtime/runtime.h"

 namespace v8 {
 namespace internal {

 RUNTIME_FUNCTION(Runtime_ArrayBufferGetByteLength) {
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_CHECKED(JSArrayBuffer, holder, 0);
   return holder->byte_length();
 }


 RUNTIME_FUNCTION(Runtime_ArrayBufferSliceImpl) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 4);
   CONVERT_ARG_HANDLE_CHECKED(JSArrayBuffer, source, 0);
   CONVERT_ARG_HANDLE_CHECKED(JSArrayBuffer, target, 1);
   CONVERT_NUMBER_ARG_HANDLE_CHECKED(first, 2);
   CONVERT_NUMBER_ARG_HANDLE_CHECKED(new_length, 3);

   if (source->was_neutered() || target->was_neutered()) {
     THROW_NEW_ERROR_RETURN_FAILURE(
         isolate, NewTypeError(MessageTemplate::kDetachedOperation,
                               isolate->factory()->NewStringFromAsciiChecked(
                                   "ArrayBuffer.prototype.slice")));
   }

   CHECK(!source.is_identical_to(target));
   size_t start = 0, target_length = 0;
   CHECK(TryNumberToSize(*first, &start));
   CHECK(TryNumberToSize(*new_length, &target_length));
   CHECK(NumberToSize(target->byte_length()) >= target_length);

   if (target_length == 0) return isolate->heap()->undefined_value();

   size_t source_byte_length = NumberToSize(source->byte_length());
   CHECK(start <= source_byte_length);
   CHECK(source_byte_length - start >= target_length);
   uint8_t* source_data = reinterpret_cast<uint8_t*>(source->backing_store());
   uint8_t* target_data = reinterpret_cast<uint8_t*>(target->backing_store());
   CopyBytes(target_data, source_data + start, target_length);
   return isolate->heap()->undefined_value();
 }


 RUNTIME_FUNCTION(Runtime_ArrayBufferNeuter) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(JSArrayBuffer, array_buffer, 0);
   if (array_buffer->backing_store() == NULL) {
     CHECK(Smi::kZero == array_buffer->byte_length());
     return isolate->heap()->undefined_value();
   }
   // Shared array buffers should never be neutered.
   CHECK(!array_buffer->is_shared());
   DCHECK(!array_buffer->is_external());
   void* backing_store = array_buffer->backing_store();
   size_t byte_length = NumberToSize(array_buffer->byte_length());
   array_buffer->set_is_external(true);
   isolate->heap()->UnregisterArrayBuffer(*array_buffer);
   array_buffer->Neuter();
   isolate->array_buffer_allocator()->Free(backing_store, byte_length);
   return isolate->heap()->undefined_value();
 }


 void Runtime::ArrayIdToTypeAndSize(int arrayId, ExternalArrayType* array_type,
                                    ElementsKind* fixed_elements_kind,
                                    size_t* element_size) {
   switch (arrayId) {
 #define ARRAY_ID_CASE(Type, type, TYPE, ctype, size)      \
   case ARRAY_ID_##TYPE:                                   \
     *array_type = kExternal##Type##Array;                 \
     *fixed_elements_kind = TYPE##_ELEMENTS;               \
     *element_size = size;                                 \
     break;

     TYPED_ARRAYS(ARRAY_ID_CASE)
 #undef ARRAY_ID_CASE

     default:
       UNREACHABLE();
   }
 }


 RUNTIME_FUNCTION(Runtime_TypedArrayInitialize) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 6);
   CONVERT_ARG_HANDLE_CHECKED(JSTypedArray, holder, 0);
   CONVERT_SMI_ARG_CHECKED(arrayId, 1);
   CONVERT_ARG_HANDLE_CHECKED(Object, maybe_buffer, 2);
   CONVERT_NUMBER_ARG_HANDLE_CHECKED(byte_offset_object, 3);
   CONVERT_NUMBER_ARG_HANDLE_CHECKED(byte_length_object, 4);
   CONVERT_BOOLEAN_ARG_CHECKED(initialize, 5);

   CHECK(arrayId >= Runtime::ARRAY_ID_FIRST &&
         arrayId <= Runtime::ARRAY_ID_LAST);

   ExternalArrayType array_type = kExternalInt8Array;  // Bogus initialization.
   size_t element_size = 1;                            // Bogus initialization.
   ElementsKind fixed_elements_kind = INT8_ELEMENTS;  // Bogus initialization.
   Runtime::ArrayIdToTypeAndSize(arrayId, &array_type, &fixed_elements_kind,
                                 &element_size);
   CHECK(holder->map()->elements_kind() == fixed_elements_kind);

   size_t byte_offset = 0;
   size_t byte_length = 0;
   CHECK(TryNumberToSize(*byte_offset_object, &byte_offset));
   CHECK(TryNumberToSize(*byte_length_object, &byte_length));

   if (maybe_buffer->IsJSArrayBuffer()) {
     Handle<JSArrayBuffer> buffer = Handle<JSArrayBuffer>::cast(maybe_buffer);
     size_t array_buffer_byte_length = NumberToSize(buffer->byte_length());
     CHECK(byte_offset <= array_buffer_byte_length);
     CHECK(array_buffer_byte_length - byte_offset >= byte_length);
   } else {
     CHECK(maybe_buffer->IsNull(isolate));
   }

   CHECK(byte_length % element_size == 0);
   size_t length = byte_length / element_size;

   if (length > static_cast<unsigned>(Smi::kMaxValue)) {
     THROW_NEW_ERROR_RETURN_FAILURE(
         isolate, NewRangeError(MessageTemplate::kInvalidTypedArrayLength));
   }

   // All checks are done, now we can modify objects.

   DCHECK_EQ(v8::ArrayBufferView::kInternalFieldCount,
             holder->GetInternalFieldCount());
   for (int i = 0; i < v8::ArrayBufferView::kInternalFieldCount; i++) {
     holder->SetInternalField(i, Smi::kZero);
   }
   Handle<Object> length_obj = isolate->factory()->NewNumberFromSize(length);
   holder->set_length(*length_obj);
   holder->set_byte_offset(*byte_offset_object);
   holder->set_byte_length(*byte_length_object);

   if (!maybe_buffer->IsNull(isolate)) {
     Handle<JSArrayBuffer> buffer = Handle<JSArrayBuffer>::cast(maybe_buffer);
     holder->set_buffer(*buffer);

     Handle<FixedTypedArrayBase> elements =
         isolate->factory()->NewFixedTypedArrayWithExternalPointer(
             static_cast<int>(length), array_type,
             static_cast<uint8_t*>(buffer->backing_store()) + byte_offset);
     holder->set_elements(*elements);
   } else {
     Handle<JSArrayBuffer> buffer = isolate->factory()->NewJSArrayBuffer();
     JSArrayBuffer::Setup(buffer, isolate, true, NULL, byte_length,
                          SharedFlag::kNotShared);
     holder->set_buffer(*buffer);
     Handle<FixedTypedArrayBase> elements =
         isolate->factory()->NewFixedTypedArray(static_cast<int>(length),
                                                array_type, initialize);
     holder->set_elements(*elements);
   }
   return isolate->heap()->undefined_value();
 }


 // Initializes a typed array from an array-like object.
 // If an array-like object happens to be a typed array of the same type,
 // initializes backing store using memove.
 //
 // Returns true if backing store was initialized or false otherwise.
 RUNTIME_FUNCTION(Runtime_TypedArrayInitializeFromArrayLike) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 4);
   CONVERT_ARG_HANDLE_CHECKED(JSTypedArray, holder, 0);
   CONVERT_SMI_ARG_CHECKED(arrayId, 1);
   CONVERT_ARG_HANDLE_CHECKED(Object, source, 2);
   CONVERT_NUMBER_ARG_HANDLE_CHECKED(length_obj, 3);

   CHECK(arrayId >= Runtime::ARRAY_ID_FIRST &&
         arrayId <= Runtime::ARRAY_ID_LAST);

   ExternalArrayType array_type = kExternalInt8Array;  // Bogus initialization.
   size_t element_size = 1;                            // Bogus initialization.
   ElementsKind fixed_elements_kind = INT8_ELEMENTS;  // Bogus initialization.
   Runtime::ArrayIdToTypeAndSize(arrayId, &array_type, &fixed_elements_kind,
                                 &element_size);

   CHECK(holder->map()->elements_kind() == fixed_elements_kind);

   Handle<JSArrayBuffer> buffer = isolate->factory()->NewJSArrayBuffer();
   size_t length = 0;
   if (source->IsJSTypedArray() &&
       JSTypedArray::cast(*source)->type() == array_type) {
     length = JSTypedArray::cast(*source)->length_value();
   } else {
     CHECK(TryNumberToSize(*length_obj, &length));
   }

   if ((length > static_cast<unsigned>(Smi::kMaxValue)) ||
       (length > (kMaxInt / element_size))) {
     THROW_NEW_ERROR_RETURN_FAILURE(
         isolate, NewRangeError(MessageTemplate::kInvalidTypedArrayLength));
   }
   size_t byte_length = length * element_size;

   DCHECK_EQ(v8::ArrayBufferView::kInternalFieldCount,
             holder->GetInternalFieldCount());
   for (int i = 0; i < v8::ArrayBufferView::kInternalFieldCount; i++) {
     holder->SetInternalField(i, Smi::kZero);
   }

   // NOTE: not initializing backing store.
   // We assume that the caller of this function will initialize holder
   // with the loop
   //      for(i = 0; i < length; i++) { holder[i] = source[i]; }
   // We assume that the caller of this function is always a typed array
   // constructor.
   // If source is a typed array, this loop will always run to completion,
   // so we are sure that the backing store will be initialized.
   // Otherwise, the indexing operation might throw, so the loop will not
   // run to completion and the typed array might remain partly initialized.
   // However we further assume that the caller of this function is a typed array
   // constructor, and the exception will propagate out of the constructor,
   // therefore uninitialized memory will not be accessible by a user program.
   //
   // TODO(dslomov): revise this once we support subclassing.

   if (!JSArrayBuffer::SetupAllocatingData(buffer, isolate, byte_length,
                                           false)) {
     THROW_NEW_ERROR_RETURN_FAILURE(
         isolate, NewRangeError(MessageTemplate::kInvalidArrayBufferLength));
   }

   holder->set_buffer(*buffer);
   holder->set_byte_offset(Smi::kZero);
   Handle<Object> byte_length_obj(
       isolate->factory()->NewNumberFromSize(byte_length));
   holder->set_byte_length(*byte_length_obj);
   length_obj = isolate->factory()->NewNumberFromSize(length);
   holder->set_length(*length_obj);

   Handle<FixedTypedArrayBase> elements =
       isolate->factory()->NewFixedTypedArrayWithExternalPointer(
           static_cast<int>(length), array_type,
           static_cast<uint8_t*>(buffer->backing_store()));
   holder->set_elements(*elements);

   if (source->IsJSTypedArray()) {
     Handle<JSTypedArray> typed_array(JSTypedArray::cast(*source));

     if (typed_array->type() == holder->type()) {
       uint8_t* backing_store =
           static_cast<uint8_t*>(typed_array->GetBuffer()->backing_store());
       size_t source_byte_offset = NumberToSize(typed_array->byte_offset());
       memcpy(buffer->backing_store(), backing_store + source_byte_offset,
              byte_length);
       return isolate->heap()->true_value();
     }
   }

   return isolate->heap()->false_value();
 }


 #define BUFFER_VIEW_GETTER(Type, getter, accessor)   \
   RUNTIME_FUNCTION(Runtime_##Type##Get##getter) {    \
     HandleScope scope(isolate);                      \
     DCHECK_EQ(1, args.length());                     \
     CONVERT_ARG_HANDLE_CHECKED(JS##Type, holder, 0); \
     return holder->accessor();                       \
   }

 BUFFER_VIEW_GETTER(ArrayBufferView, ByteLength, byte_length)
 BUFFER_VIEW_GETTER(ArrayBufferView, ByteOffset, byte_offset)
 BUFFER_VIEW_GETTER(TypedArray, Length, length)

 #undef BUFFER_VIEW_GETTER

 RUNTIME_FUNCTION(Runtime_TypedArrayGetBuffer) {
   HandleScope scope(isolate);
   DCHECK_EQ(1, args.length());
   CONVERT_ARG_HANDLE_CHECKED(JSTypedArray, holder, 0);
   return *holder->GetBuffer();
 }


 // Return codes for Runtime_TypedArraySetFastCases.
 // Should be synchronized with typedarray.js natives.
 enum TypedArraySetResultCodes {
   // Set from typed array of the same type.
   // This is processed by TypedArraySetFastCases
   TYPED_ARRAY_SET_TYPED_ARRAY_SAME_TYPE = 0,
   // Set from typed array of the different type, overlapping in memory.
   TYPED_ARRAY_SET_TYPED_ARRAY_OVERLAPPING = 1,
   // Set from typed array of the different type, non-overlapping.
   TYPED_ARRAY_SET_TYPED_ARRAY_NONOVERLAPPING = 2,
   // Set from non-typed array.
   TYPED_ARRAY_SET_NON_TYPED_ARRAY = 3
 };


 RUNTIME_FUNCTION(Runtime_TypedArraySetFastCases) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 3);
   if (!args[0]->IsJSTypedArray()) {
     THROW_NEW_ERROR_RETURN_FAILURE(
         isolate, NewTypeError(MessageTemplate::kNotTypedArray));
   }

   if (!args[1]->IsJSTypedArray())
     return Smi::FromInt(TYPED_ARRAY_SET_NON_TYPED_ARRAY);

   CONVERT_ARG_HANDLE_CHECKED(JSTypedArray, target_obj, 0);
   CONVERT_ARG_HANDLE_CHECKED(JSTypedArray, source_obj, 1);
   CONVERT_NUMBER_ARG_HANDLE_CHECKED(offset_obj, 2);

   Handle<JSTypedArray> target(JSTypedArray::cast(*target_obj));
   Handle<JSTypedArray> source(JSTypedArray::cast(*source_obj));
   size_t offset = 0;
   CHECK(TryNumberToSize(*offset_obj, &offset));
   size_t target_length = target->length_value();
   size_t source_length = source->length_value();
   size_t target_byte_length = NumberToSize(target->byte_length());
   size_t source_byte_length = NumberToSize(source->byte_length());
   if (offset > target_length || offset + source_length > target_length ||
       offset + source_length < offset) {  // overflow
     THROW_NEW_ERROR_RETURN_FAILURE(
         isolate, NewRangeError(MessageTemplate::kTypedArraySetSourceTooLarge));
   }

   size_t target_offset = NumberToSize(target->byte_offset());
   size_t source_offset = NumberToSize(source->byte_offset());
   uint8_t* target_base =
       static_cast<uint8_t*>(target->GetBuffer()->backing_store()) +
       target_offset;
   uint8_t* source_base =
       static_cast<uint8_t*>(source->GetBuffer()->backing_store()) +
       source_offset;

   // Typed arrays of the same type: use memmove.
   if (target->type() == source->type()) {
     memmove(target_base + offset * target->element_size(), source_base,
             source_byte_length);
     return Smi::FromInt(TYPED_ARRAY_SET_TYPED_ARRAY_SAME_TYPE);
   }

   // Typed arrays of different types over the same backing store
   if ((source_base <= target_base &&
        source_base + source_byte_length > target_base) ||
       (target_base <= source_base &&
        target_base + target_byte_length > source_base)) {
     // We do not support overlapping ArrayBuffers
     DCHECK(target->GetBuffer()->backing_store() ==
            source->GetBuffer()->backing_store());
     return Smi::FromInt(TYPED_ARRAY_SET_TYPED_ARRAY_OVERLAPPING);
   } else {  // Non-overlapping typed arrays
     return Smi::FromInt(TYPED_ARRAY_SET_TYPED_ARRAY_NONOVERLAPPING);
   }
 }


 RUNTIME_FUNCTION(Runtime_TypedArrayMaxSizeInHeap) {
   DCHECK(args.length() == 0);
   DCHECK_OBJECT_SIZE(FLAG_typed_array_max_size_in_heap +
                      FixedTypedArrayBase::kDataOffset);
   return Smi::FromInt(FLAG_typed_array_max_size_in_heap);
 }


 RUNTIME_FUNCTION(Runtime_IsTypedArray) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   return isolate->heap()->ToBoolean(args[0]->IsJSTypedArray());
 }


 RUNTIME_FUNCTION(Runtime_IsSharedTypedArray) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   return isolate->heap()->ToBoolean(
       args[0]->IsJSTypedArray() &&
       JSTypedArray::cast(args[0])->GetBuffer()->is_shared());
 }


 RUNTIME_FUNCTION(Runtime_IsSharedIntegerTypedArray) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   if (!args[0]->IsJSTypedArray()) {
     return isolate->heap()->false_value();
   }

   Handle<JSTypedArray> obj(JSTypedArray::cast(args[0]));
   return isolate->heap()->ToBoolean(obj->GetBuffer()->is_shared() &&
                                     obj->type() != kExternalFloat32Array &&
                                     obj->type() != kExternalFloat64Array &&
                                     obj->type() != kExternalUint8ClampedArray);
 }


 RUNTIME_FUNCTION(Runtime_IsSharedInteger32TypedArray) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   if (!args[0]->IsJSTypedArray()) {
     return isolate->heap()->false_value();
   }

   Handle<JSTypedArray> obj(JSTypedArray::cast(args[0]));
   return isolate->heap()->ToBoolean(obj->GetBuffer()->is_shared() &&
                                     obj->type() == kExternalInt32Array);
 }

 }  // namespace internal
 }  // namespace v8
	// Copyright 2014 the V8 project authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#include "src/runtime/runtime-utils.h"

	#include "src/arguments.h"
	#include "src/factory.h"
	#include "src/messages.h"
	#include "src/objects-inl.h"
	#include "src/runtime/runtime.h"

	namespace v8 {
	namespace internal {

	RUNTIME_FUNCTION(Runtime_ArrayBufferGetByteLength) {
	SealHandleScope shs(isolate);
	DCHECK(args.length() == 1);
	CONVERT_ARG_CHECKED(JSArrayBuffer, holder, 0);
	return holder->byte_length();
	}


	RUNTIME_FUNCTION(Runtime_ArrayBufferSliceImpl) {
	HandleScope scope(isolate);
	DCHECK(args.length() == 4);
	CONVERT_ARG_HANDLE_CHECKED(JSArrayBuffer, source, 0);
	CONVERT_ARG_HANDLE_CHECKED(JSArrayBuffer, target, 1);
	CONVERT_NUMBER_ARG_HANDLE_CHECKED(first, 2);
	CONVERT_NUMBER_ARG_HANDLE_CHECKED(new_length, 3);

	if (source->was_neutered() \|\| target->was_neutered()) {
	THROW_NEW_ERROR_RETURN_FAILURE(
	isolate, NewTypeError(MessageTemplate::kDetachedOperation,
	isolate->factory()->NewStringFromAsciiChecked(
	"ArrayBuffer.prototype.slice")));
	}

	CHECK(!source.is_identical_to(target));
	size_t start = 0, target_length = 0;
	CHECK(TryNumberToSize(*first, &start));
	CHECK(TryNumberToSize(*new_length, &target_length));
	CHECK(NumberToSize(target->byte_length()) >= target_length);

	if (target_length == 0) return isolate->heap()->undefined_value();

	size_t source_byte_length = NumberToSize(source->byte_length());
	CHECK(start <= source_byte_length);
	CHECK(source_byte_length - start >= target_length);
	uint8_t* source_data = reinterpret_cast<uint8_t*>(source->backing_store());
	uint8_t* target_data = reinterpret_cast<uint8_t*>(target->backing_store());
	CopyBytes(target_data, source_data + start, target_length);
	return isolate->heap()->undefined_value();
	}


	RUNTIME_FUNCTION(Runtime_ArrayBufferNeuter) {
	HandleScope scope(isolate);
	DCHECK(args.length() == 1);
	CONVERT_ARG_HANDLE_CHECKED(JSArrayBuffer, array_buffer, 0);
	if (array_buffer->backing_store() == NULL) {
	CHECK(Smi::kZero == array_buffer->byte_length());
	return isolate->heap()->undefined_value();
	}
	// Shared array buffers should never be neutered.
	CHECK(!array_buffer->is_shared());
	DCHECK(!array_buffer->is_external());
	void* backing_store = array_buffer->backing_store();
	size_t byte_length = NumberToSize(array_buffer->byte_length());
	array_buffer->set_is_external(true);
	isolate->heap()->UnregisterArrayBuffer(*array_buffer);
	array_buffer->Neuter();
	isolate->array_buffer_allocator()->Free(backing_store, byte_length);
	return isolate->heap()->undefined_value();
	}


	void Runtime::ArrayIdToTypeAndSize(int arrayId, ExternalArrayType* array_type,
	ElementsKind* fixed_elements_kind,
	size_t* element_size) {
	switch (arrayId) {
	#define ARRAY_ID_CASE(Type, type, TYPE, ctype, size) \
	case ARRAY_ID_##TYPE: \
	*array_type = kExternal##Type##Array; \
	*fixed_elements_kind = TYPE##_ELEMENTS; \
	*element_size = size; \
	break;

	TYPED_ARRAYS(ARRAY_ID_CASE)
	#undef ARRAY_ID_CASE

	default:
	UNREACHABLE();
	}
	}


	RUNTIME_FUNCTION(Runtime_TypedArrayInitialize) {
	HandleScope scope(isolate);
	DCHECK(args.length() == 6);
	CONVERT_ARG_HANDLE_CHECKED(JSTypedArray, holder, 0);
	CONVERT_SMI_ARG_CHECKED(arrayId, 1);
	CONVERT_ARG_HANDLE_CHECKED(Object, maybe_buffer, 2);
	CONVERT_NUMBER_ARG_HANDLE_CHECKED(byte_offset_object, 3);
	CONVERT_NUMBER_ARG_HANDLE_CHECKED(byte_length_object, 4);
	CONVERT_BOOLEAN_ARG_CHECKED(initialize, 5);

	CHECK(arrayId >= Runtime::ARRAY_ID_FIRST &&
	arrayId <= Runtime::ARRAY_ID_LAST);

	ExternalArrayType array_type = kExternalInt8Array; // Bogus initialization.
	size_t element_size = 1; // Bogus initialization.
	ElementsKind fixed_elements_kind = INT8_ELEMENTS; // Bogus initialization.
	Runtime::ArrayIdToTypeAndSize(arrayId, &array_type, &fixed_elements_kind,
	&element_size);
	CHECK(holder->map()->elements_kind() == fixed_elements_kind);

	size_t byte_offset = 0;
	size_t byte_length = 0;
	CHECK(TryNumberToSize(*byte_offset_object, &byte_offset));
	CHECK(TryNumberToSize(*byte_length_object, &byte_length));

	if (maybe_buffer->IsJSArrayBuffer()) {
	Handle<JSArrayBuffer> buffer = Handle<JSArrayBuffer>::cast(maybe_buffer);
	size_t array_buffer_byte_length = NumberToSize(buffer->byte_length());
	CHECK(byte_offset <= array_buffer_byte_length);
	CHECK(array_buffer_byte_length - byte_offset >= byte_length);
	} else {
	CHECK(maybe_buffer->IsNull(isolate));
	}

	CHECK(byte_length % element_size == 0);
	size_t length = byte_length / element_size;

	if (length > static_cast<unsigned>(Smi::kMaxValue)) {
	THROW_NEW_ERROR_RETURN_FAILURE(
	isolate, NewRangeError(MessageTemplate::kInvalidTypedArrayLength));
	}

	// All checks are done, now we can modify objects.

	DCHECK_EQ(v8::ArrayBufferView::kInternalFieldCount,
	holder->GetInternalFieldCount());
	for (int i = 0; i < v8::ArrayBufferView::kInternalFieldCount; i++) {
	holder->SetInternalField(i, Smi::kZero);
	}
	Handle<Object> length_obj = isolate->factory()->NewNumberFromSize(length);
	holder->set_length(*length_obj);
	holder->set_byte_offset(*byte_offset_object);
	holder->set_byte_length(*byte_length_object);

	if (!maybe_buffer->IsNull(isolate)) {
	Handle<JSArrayBuffer> buffer = Handle<JSArrayBuffer>::cast(maybe_buffer);
	holder->set_buffer(*buffer);

	Handle<FixedTypedArrayBase> elements =
	isolate->factory()->NewFixedTypedArrayWithExternalPointer(
	static_cast<int>(length), array_type,
	static_cast<uint8_t*>(buffer->backing_store()) + byte_offset);
	holder->set_elements(*elements);
	} else {
	Handle<JSArrayBuffer> buffer = isolate->factory()->NewJSArrayBuffer();
	JSArrayBuffer::Setup(buffer, isolate, true, NULL, byte_length,
	SharedFlag::kNotShared);
	holder->set_buffer(*buffer);
	Handle<FixedTypedArrayBase> elements =
	isolate->factory()->NewFixedTypedArray(static_cast<int>(length),
	array_type, initialize);
	holder->set_elements(*elements);
	}
	return isolate->heap()->undefined_value();
	}


	// Initializes a typed array from an array-like object.
	// If an array-like object happens to be a typed array of the same type,
	// initializes backing store using memove.
	//
	// Returns true if backing store was initialized or false otherwise.
	RUNTIME_FUNCTION(Runtime_TypedArrayInitializeFromArrayLike) {
	HandleScope scope(isolate);
	DCHECK(args.length() == 4);
	CONVERT_ARG_HANDLE_CHECKED(JSTypedArray, holder, 0);
	CONVERT_SMI_ARG_CHECKED(arrayId, 1);
	CONVERT_ARG_HANDLE_CHECKED(Object, source, 2);
	CONVERT_NUMBER_ARG_HANDLE_CHECKED(length_obj, 3);

	CHECK(arrayId >= Runtime::ARRAY_ID_FIRST &&
	arrayId <= Runtime::ARRAY_ID_LAST);

	ExternalArrayType array_type = kExternalInt8Array; // Bogus initialization.
	size_t element_size = 1; // Bogus initialization.
	ElementsKind fixed_elements_kind = INT8_ELEMENTS; // Bogus initialization.
	Runtime::ArrayIdToTypeAndSize(arrayId, &array_type, &fixed_elements_kind,
	&element_size);

	CHECK(holder->map()->elements_kind() == fixed_elements_kind);

	Handle<JSArrayBuffer> buffer = isolate->factory()->NewJSArrayBuffer();
	size_t length = 0;
	if (source->IsJSTypedArray() &&
	JSTypedArray::cast(*source)->type() == array_type) {
	length = JSTypedArray::cast(*source)->length_value();
	} else {
	CHECK(TryNumberToSize(*length_obj, &length));
	}

	if ((length > static_cast<unsigned>(Smi::kMaxValue)) \|\|
	(length > (kMaxInt / element_size))) {
	THROW_NEW_ERROR_RETURN_FAILURE(
	isolate, NewRangeError(MessageTemplate::kInvalidTypedArrayLength));
	}
	size_t byte_length = length * element_size;

	DCHECK_EQ(v8::ArrayBufferView::kInternalFieldCount,
	holder->GetInternalFieldCount());
	for (int i = 0; i < v8::ArrayBufferView::kInternalFieldCount; i++) {
	holder->SetInternalField(i, Smi::kZero);
	}

	// NOTE: not initializing backing store.
	// We assume that the caller of this function will initialize holder
	// with the loop
	// for(i = 0; i < length; i++) { holder[i] = source[i]; }
	// We assume that the caller of this function is always a typed array
	// constructor.
	// If source is a typed array, this loop will always run to completion,
	// so we are sure that the backing store will be initialized.
	// Otherwise, the indexing operation might throw, so the loop will not
	// run to completion and the typed array might remain partly initialized.
	// However we further assume that the caller of this function is a typed array
	// constructor, and the exception will propagate out of the constructor,
	// therefore uninitialized memory will not be accessible by a user program.
	//
	// TODO(dslomov): revise this once we support subclassing.

	if (!JSArrayBuffer::SetupAllocatingData(buffer, isolate, byte_length,
	false)) {
	THROW_NEW_ERROR_RETURN_FAILURE(
	isolate, NewRangeError(MessageTemplate::kInvalidArrayBufferLength));
	}

	holder->set_buffer(*buffer);
	holder->set_byte_offset(Smi::kZero);
	Handle<Object> byte_length_obj(
	isolate->factory()->NewNumberFromSize(byte_length));
	holder->set_byte_length(*byte_length_obj);
	length_obj = isolate->factory()->NewNumberFromSize(length);
	holder->set_length(*length_obj);

	Handle<FixedTypedArrayBase> elements =
	isolate->factory()->NewFixedTypedArrayWithExternalPointer(
	static_cast<int>(length), array_type,
	static_cast<uint8_t*>(buffer->backing_store()));
	holder->set_elements(*elements);

	if (source->IsJSTypedArray()) {
	Handle<JSTypedArray> typed_array(JSTypedArray::cast(*source));

	if (typed_array->type() == holder->type()) {
	uint8_t* backing_store =
	static_cast<uint8_t*>(typed_array->GetBuffer()->backing_store());
	size_t source_byte_offset = NumberToSize(typed_array->byte_offset());
	memcpy(buffer->backing_store(), backing_store + source_byte_offset,
	byte_length);
	return isolate->heap()->true_value();
	}
	}

	return isolate->heap()->false_value();
	}


	#define BUFFER_VIEW_GETTER(Type, getter, accessor) \
	RUNTIME_FUNCTION(Runtime_##Type##Get##getter) { \
	HandleScope scope(isolate); \
	DCHECK_EQ(1, args.length()); \
	CONVERT_ARG_HANDLE_CHECKED(JS##Type, holder, 0); \
	return holder->accessor(); \
	}

	BUFFER_VIEW_GETTER(ArrayBufferView, ByteLength, byte_length)
	BUFFER_VIEW_GETTER(ArrayBufferView, ByteOffset, byte_offset)
	BUFFER_VIEW_GETTER(TypedArray, Length, length)

	#undef BUFFER_VIEW_GETTER

	RUNTIME_FUNCTION(Runtime_TypedArrayGetBuffer) {
	HandleScope scope(isolate);
	DCHECK_EQ(1, args.length());
	CONVERT_ARG_HANDLE_CHECKED(JSTypedArray, holder, 0);
	return *holder->GetBuffer();
	}


	// Return codes for Runtime_TypedArraySetFastCases.
	// Should be synchronized with typedarray.js natives.
	enum TypedArraySetResultCodes {
	// Set from typed array of the same type.
	// This is processed by TypedArraySetFastCases
	TYPED_ARRAY_SET_TYPED_ARRAY_SAME_TYPE = 0,
	// Set from typed array of the different type, overlapping in memory.
	TYPED_ARRAY_SET_TYPED_ARRAY_OVERLAPPING = 1,
	// Set from typed array of the different type, non-overlapping.
	TYPED_ARRAY_SET_TYPED_ARRAY_NONOVERLAPPING = 2,
	// Set from non-typed array.
	TYPED_ARRAY_SET_NON_TYPED_ARRAY = 3
	};


	RUNTIME_FUNCTION(Runtime_TypedArraySetFastCases) {
	HandleScope scope(isolate);
	DCHECK(args.length() == 3);
	if (!args[0]->IsJSTypedArray()) {
	THROW_NEW_ERROR_RETURN_FAILURE(
	isolate, NewTypeError(MessageTemplate::kNotTypedArray));
	}

	if (!args[1]->IsJSTypedArray())
	return Smi::FromInt(TYPED_ARRAY_SET_NON_TYPED_ARRAY);

	CONVERT_ARG_HANDLE_CHECKED(JSTypedArray, target_obj, 0);
	CONVERT_ARG_HANDLE_CHECKED(JSTypedArray, source_obj, 1);
	CONVERT_NUMBER_ARG_HANDLE_CHECKED(offset_obj, 2);

	Handle<JSTypedArray> target(JSTypedArray::cast(*target_obj));
	Handle<JSTypedArray> source(JSTypedArray::cast(*source_obj));
	size_t offset = 0;
	CHECK(TryNumberToSize(*offset_obj, &offset));
	size_t target_length = target->length_value();
	size_t source_length = source->length_value();
	size_t target_byte_length = NumberToSize(target->byte_length());
	size_t source_byte_length = NumberToSize(source->byte_length());
	if (offset > target_length \|\| offset + source_length > target_length \|\|
	offset + source_length < offset) { // overflow
	THROW_NEW_ERROR_RETURN_FAILURE(
	isolate, NewRangeError(MessageTemplate::kTypedArraySetSourceTooLarge));
	}

	size_t target_offset = NumberToSize(target->byte_offset());
	size_t source_offset = NumberToSize(source->byte_offset());
	uint8_t* target_base =
	static_cast<uint8_t*>(target->GetBuffer()->backing_store()) +
	target_offset;
	uint8_t* source_base =
	static_cast<uint8_t*>(source->GetBuffer()->backing_store()) +
	source_offset;

	// Typed arrays of the same type: use memmove.
	if (target->type() == source->type()) {
	memmove(target_base + offset * target->element_size(), source_base,
	source_byte_length);
	return Smi::FromInt(TYPED_ARRAY_SET_TYPED_ARRAY_SAME_TYPE);
	}

	// Typed arrays of different types over the same backing store
	if ((source_base <= target_base &&
	source_base + source_byte_length > target_base) \|\|
	(target_base <= source_base &&
	target_base + target_byte_length > source_base)) {
	// We do not support overlapping ArrayBuffers
	DCHECK(target->GetBuffer()->backing_store() ==
	source->GetBuffer()->backing_store());
	return Smi::FromInt(TYPED_ARRAY_SET_TYPED_ARRAY_OVERLAPPING);
	} else { // Non-overlapping typed arrays
	return Smi::FromInt(TYPED_ARRAY_SET_TYPED_ARRAY_NONOVERLAPPING);
	}
	}


	RUNTIME_FUNCTION(Runtime_TypedArrayMaxSizeInHeap) {
	DCHECK(args.length() == 0);
	DCHECK_OBJECT_SIZE(FLAG_typed_array_max_size_in_heap +
	FixedTypedArrayBase::kDataOffset);
	return Smi::FromInt(FLAG_typed_array_max_size_in_heap);
	}


	RUNTIME_FUNCTION(Runtime_IsTypedArray) {
	HandleScope scope(isolate);
	DCHECK(args.length() == 1);
	return isolate->heap()->ToBoolean(args[0]->IsJSTypedArray());
	}


	RUNTIME_FUNCTION(Runtime_IsSharedTypedArray) {
	HandleScope scope(isolate);
	DCHECK(args.length() == 1);
	return isolate->heap()->ToBoolean(
	args[0]->IsJSTypedArray() &&
	JSTypedArray::cast(args[0])->GetBuffer()->is_shared());
	}


	RUNTIME_FUNCTION(Runtime_IsSharedIntegerTypedArray) {
	HandleScope scope(isolate);
	DCHECK(args.length() == 1);
	if (!args[0]->IsJSTypedArray()) {
	return isolate->heap()->false_value();
	}

	Handle<JSTypedArray> obj(JSTypedArray::cast(args[0]));
	return isolate->heap()->ToBoolean(obj->GetBuffer()->is_shared() &&
	obj->type() != kExternalFloat32Array &&
	obj->type() != kExternalFloat64Array &&
	obj->type() != kExternalUint8ClampedArray);
	}


	RUNTIME_FUNCTION(Runtime_IsSharedInteger32TypedArray) {
	HandleScope scope(isolate);
	DCHECK(args.length() == 1);
	if (!args[0]->IsJSTypedArray()) {
	return isolate->heap()->false_value();
	}

	Handle<JSTypedArray> obj(JSTypedArray::cast(args[0]));
	return isolate->heap()->ToBoolean(obj->GetBuffer()->is_shared() &&
	obj->type() == kExternalInt32Array);
	}

	} // namespace internal
	} // namespace v8